Surface Investigation of Aerospace 7075-T6 Aluminum Anodized in the Presence of Glycols

The effect of glycol derivatives including ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) has been investigated on the characterization Al₂O₃ coating of anodized 7075-T6 aluminum in 20% w/w sulfuric acid, current density 4 A/dm², and time 50 min. The thickness and hardness of Al₂O₃ layer measured and characterized by X-ray diffraction patterns, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The Tafle plots of linear polarization method and electrochemical impedance spectroscopy technique used to investigate the resistance to corrosion Al₂O₃ layer. The results showed that the thickness, hardness, and resistance to corrosion of Al₂O₃ film are increased, respectively, 30, 42, and 40% in the presence of glycols (10% w/w). The ratio of dielectric constant (ε) to dynamic viscosity (η) of TEG, DEG, and EG, respectively, is 0.48, 0.89, and 2.28 that is due to improvement of anodized aluminum in the presence glycol derivatives as EG > DEG > TEG.